1. Field of the Invention
The present invention relates to a vehicle drive assist system which provides drive assist for a driver by recognizing surrounding environment of a subject vehicle.
2. Description of the Related Art
In recent years, a technique has been developed and put into the practical use, the technique which recognizes a three-dimensional object, such as an obstruction or a front vehicle, by detecting external surrounding environment of a vehicle such as an automobile, with a camera or a laser radar mounted on the vehicle, and which provides drive assist control of, for example, alerting, automatic braking, and automatic steering to prevent collision, thereby increasing the safety.
With such a drive assist control, collision is typically predicted based on relative positions of a subject vehicle and an obstruction, and speed information of the subject vehicle. Using the prediction result, the alerting and control for preventive safety are provided. For example, Japanese Unexamined Patent Application Publication No. 2000-357299 discloses a technique which predicts a position at which a subject vehicle collides with an oncoming vehicle, based on a relative positional relationship between the subject vehicle and the oncoming vehicle, and a vehicle speed of the subject vehicle.
A sensor for recognizing surrounding environment of the subject vehicle typically uses a stereo camera, a millimeter wave radar, a laser radar, etc. Unfortunately, a speed detection accuracy of such a sensor is insufficient in a lateral direction. It is difficult to highly accurately predict a possibility of collision between the subject vehicle and a movable body such as an oncoming vehicle, with the technique of related art disclosed in Japanese Unexamined Patent Application Publication No. 2000-357299. Hence, erroneous alerting and control may likely occur.